Vehicle control system and vehicle control system design method

ABSTRACT

A design method for a vehicle control system includes constructing a daisy chain trunk network by a central processing unit and a plurality of zone ECUs, calculating a first activation time from when a network is sequentially activated from a predetermined zone ECU to when the central processing unit is activated, calculating a second activation time from when a network is sequentially activated from the central processing unit to when the zone ECU is activated, and determining a connection destination of an information acquisition unit and a connection destination of an in-vehicle device from the zone ECUs in a manner that a total time of the first activation time and the second activation time is less than a predetermined delay time.

TECHNICAL FIELD

The technology disclosed herein relates to a vehicle control system anda design method for a vehicle control system.

BACKGROUND ART

Patent Literature 1 discloses a technique in which a plurality ofdomains divided on the basis of the function of an in-vehicle device areprovided, a domain control unit is provided for each domain, and aplurality of the domain control units are controlled by an integratedcontrol unit. In Patent Literature 1, for example, each device controlunit is implemented by a single or a plurality of ECUs, and these ECUsare connected by a hierarchical network.

Patent Literature 2 discloses a technique of providing a gateway or anetwork hub (HUB) that relays data transmission and reception betweennodes in different networks in an in-vehicle network system.

CITATION LIST Patent Literature

-   Patent Literature 1: JP 2017-61278 A-   Patent Literature 2: JP 2017-212725 A

SUMMARY Technical Problem

Recently, technology development related to vehicle automation(including partial automation) that controls a vehicle on the basis ofenvironment information inside and outside the vehicle, driverinformation (hereinafter, simply and collectively referred to as“vehicle interior and exterior environment information”), and the like,including an autonomous driving system, has been promoted. In general,in the vehicle automation technology, the vehicle interior and exteriorenvironment information (including information about a driver'soperation) is acquired by a camera, a sensor, or the like (hereinafter,simply referred to as “sensor”), arithmetic processing is performed onthe basis of the acquired vehicle interior and exterior environmentinformation, and various actuators mounted on the vehicle are controlledon the basis of the arithmetic result. In the future, the arithmeticprocessing function and the control function of each actuator will beintegrated into a central processing unit that integrally manages theoperation of the entire vehicle.

Meanwhile, it is not realistic to directly connect the sensors and theactuators to the central processing unit in which functions areintegrated as described above, because the number of signal linesincreases.

Consequently, as in Patent Literature 2, the in-vehicle network in whichthe electronic control unit (ECU) that functions as a network hub deviceor a gateway device is provided, and communication is performed via theECU is assumed to be constructed. That is, it is assumed that the ECUsare connected in a daisy chain layout. Furthermore, it is assumed thatthe trunk network is configured with a high-speed interface such asEthernet (registered trademark), while a conventional CAN interfaceremains at an end portion or the like in the trunk network.

As a result, it is assumed that a latency occurs when data istransmitted and received, or a protocol conversion time for protocolconversion is generated. In addition, for example, for the purpose ofreducing power consumption, each ECU is sometimes put into a sleep stateor a power-off state when the vehicle is stopped or the like. In thein-vehicle network, each function is sometimes activated on the basis ofa sensor, a switch, or the like installed in each part of the vehicle,and in that case, the activation delay time due to the propagation of anactivation signal may be a problem in a network configuration with adaisy chain connection.

The technology disclosed herein has been made in view of such a point,and an object thereof is to provide a design method for incorporating acontrol function of an actuator in a central processing unit.

Solution to Problem

In order to solve the above problem, the technology disclosed hereinrelates to a design method for a vehicle control system including aplurality of zone ECUs each of which is disposed in each predeterminedzone of a vehicle and a central processing unit that integrally controlsthe zone ECUs, the design method operating an in-vehicle deviceinstalled in the vehicle in accordance with an activation signal from aninformation acquisition unit installed in the vehicle, the design methodincluding constructing a trunk network by connecting the centralprocessing unit and the zone ECUs in a daisy chain layout, calculating afirst activation time from when each network from a predetermined zoneECU of the zone ECUs to the central processing unit is sequentiallyactivated to when the central processing unit is activated, calculatinga second activation time from when each network from the centralprocessing unit to a predetermined zone ECU of the zone ECUs issequentially activated to when the predetermined zone ECU is activated,and determining a connection destination of the information acquisitionunit and a connection destination of the in-vehicle device from the zoneECUs in a manner that a total time of the first activation time and thesecond activation time is less than a predetermined delay time.

Furthermore, the technology disclosed herein relates to a design methodfor a vehicle control system including a plurality of zone ECUs each ofwhich is disposed in each predetermined zone of a vehicle and a centralprocessing unit that integrally controls the zone ECUs, the designmethod operating an in-vehicle device installed in the vehicle inaccordance with an activation signal from an information acquisitionunit installed in the vehicle, where constructing a network byconnecting the central processing unit and the zone ECUs in a daisychain layout includes setting a network path of a first network and anetwork path of a second network in a manner that a total time of afirst activation time from when the first network from a first zone ECUof the zone ECUs, the first zone ECU receiving an activation signal fromthe information acquisition unit, to the central processing unit issequentially activated to when the central processing unit is activatedand a second activation time from when the second network from thecentral processing unit to a second zone ECU of the zone ECUs, thesecond zone ECU outputting a control signal of the in-vehicle device, issequentially activated to when the second zone ECU is activated is lessthan a predetermined delay time.

A vehicle control system including a central processing unit thatintegrally controls an operation of a vehicle, and a plurality of zoneECUs connected to the central processing unit in a daisy chain layout,the vehicle control system operating an in-vehicle device installed inthe vehicle in accordance with an activation signal from an informationacquisition unit installed in the vehicle, wherein the zone ECUs includea first zone ECU to which the information acquisition unit is connectedand a second zone ECU to which the in-vehicle device is connected, andthe first zone ECU and the second zone ECU are set in a manner that atotal time of a first activation time from when the first zone ECUreceives the activation signal from the information acquisition unit anda first network from the first zone ECU to the central processing unitis sequentially activated to when the central processing unit isactivated and a second activation time from when the central processingunit is activated and a second network from the central processing unitto the second zone ECU is sequentially activated to when the second zoneECU is activated is less than a predetermined delay time.

According to these aspects, it is possible to configure an in-vehiclenetwork reflecting an activation delay in a complicated network systemin which a plurality of communication protocols are mixed and differentcommunication protocols are connected in a daisy chain layout.

Advantageous Effects

According to the technology disclosed herein, the design method forincorporating the control function of the actuator in the centralprocessing unit is provided.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating a configuration example of anin-vehicle network system.

FIG. 2 is a diagram illustrating a functional configuration example of afirst zone ECU.

FIG. 3 is a diagram illustrating a functional configuration example of athird zone ECU.

FIG. 4 is a diagram illustrating a functional configuration example of afifth zone ECU.

FIG. 5 is a flowchart illustrating a design method for a vehicle controlsystem according to a first embodiment.

FIG. 6 is a diagram for explaining the design method for the vehiclecontrol system according to the first embodiment.

FIG. 7 is a diagram for explaining the design method for the vehiclecontrol system according to the first embodiment.

FIG. 8 is a diagram for explaining the design method for the vehiclecontrol system according to the first embodiment.

FIG. 9 is a diagram for explaining the design method for the vehiclecontrol system according to the first embodiment.

FIG. 10 is a diagram for explaining the design method for the vehiclecontrol system according to the first embodiment.

FIG. 11 is a flowchart illustrating a design method for a vehiclecontrol system according to a second embodiment.

FIG. 12 is a diagram for explaining the design method for the vehiclecontrol system according to the second embodiment.

FIG. 13 is a diagram for explaining the design method for the vehiclecontrol system according to the second embodiment.

FIG. 14 is a diagram for explaining the design method for the vehiclecontrol system according to the second embodiment.

DESCRIPTION OF EMBODIMENTS

Hereinafter, exemplary embodiments will be described in detail withreference to the drawings. Note that, in the present specification,devices that execute traveling control, such as sensors and/or actuatorsmounted on a vehicle, are referred to as “in-vehicle devices” or simply“devices”.

First Embodiment

FIG. 1 is a diagram illustrating a configuration example of anin-vehicle network system. The in-vehicle network system illustrated inFIG. 1 is mounted on a vehicle 1 and includes a central processing unit10 and a plurality of zone ECUs 2. In the in-vehicle network system ofthe present embodiment, the vehicle 1 is divided into a plurality of(seven in the present embodiment) zones, and each zone includes the zoneECU 2. Although details will be described later, each zone ECU 2functions as a network hub device having a function to relay informationtransmitted via a network.

In the following description, the zone ECU 2 disposed in the left dashzone near the left front seat of the vehicle 1 is referred to as “firstzone ECU 21”, and the zone ECU 2 disposed in the right dash zone nearthe right front seat of the vehicle 1 is referred to as “second zone ECU22” in some cases. The zone ECU 2 disposed in the left front zone on theleft front side of the vehicle 1 is referred to as “third zone ECU 23”,and the zone ECU 2 disposed in the right front zone on the right frontside of the vehicle 1 is referred to as “fourth zone ECU 24” in somecases. The zone ECU 2 disposed in the left rear zone on the left rearside of the vehicle 1 is referred to as “fifth zone ECU 25”, and thezone ECU 2 disposed in the right rear zone on the right rear side of thevehicle 1 is referred to as “sixth zone ECU 26” in some cases. In somecases, the zone ECU 2 disposed in the console zone near the centerconsole of the vehicle 1 is referred to as “seventh zone ECU 27”. Notethat when the zone ECUs 21 to 27 are not distinguished, they are simplyreferred to as “zone ECU 2”. When the number of zones is increased ordecreased, the number of zone ECUs 2 is also increased or decreasedaccordingly.

The zone ECU 2 is configured to be able to connect in-vehicle devicessuch as a smart ECU, a smart actuator, a sensor, and an actuator, whichwill be described later. Note that the present embodiment shows anexample in which the zone ECU 2 is provided in each zone, but thepresent invention is not limited thereto, and for example, the zone ECUfor connecting an in-vehicle device corresponding to a specific functioncan be provided regardless of the zone. In addition, the zone caninclude a plurality of zone ECUs. Furthermore, the smart ECU can alsofunction as the zone ECU, or the zone ECU can also function as the smartECU.

In FIG. 1, the first zone ECU 21, the second zone ECU 22, the third zoneECU 23, and the fourth zone ECU 24 have a function as an Ethernet hubdevice (denoted as “E-EC” in FIG. 1) that transmits and receivesEthernet signals to and from the central processing unit 10. The centralprocessing unit 10 and the first zone ECU 21 are connected by anEthernet cable EB1, and the central processing unit 10 and the secondzone ECU 22 are connected by an Ethernet cable EB2. The centralprocessing unit 10 and the third zone ECU 23 are connected by anEthernet cable EB3, the central processing unit 10 and the fourth zoneECU 24 are connected by an Ethernet cable EB4, and the third zone ECU 23and the fourth zone ECU 24 are connected by an Ethernet cable EB5. Here,the Ethernet signal is a signal conforming to the Ethernet protocol.Similarly, a CAN signal to be described later is a signal conforming tothe CAN protocol, a CAN-FD signal is a signal conforming to the CAN-FDprotocol, and a local interconnect network (LIN) signal is a signalconforming to the LIN protocol.

In FIG. 1, the fifth zone ECU 25, the sixth zone ECU 26, and the seventhzone ECU 27 function as a CAN hub device (denoted as “C-EC” in FIG. 1)that transmits and receives a CAN with Flexible Data-Rate (CAN-FD)signal or a CAN (Controller Area Network) signal to and from the centralprocessing unit 10 and/or another zone ECU 2. The first zone ECU 21 andthe fifth zone ECU 25 are connected by a CAN-FD cable CB5, the secondzone ECU 22 and the sixth zone ECU 26 are connected by a CAN-FD cableCB6, and the fifth zone ECU 25 and the sixth zone ECU 26 are connectedby a CAN-FD cable CB5. The first zone ECU 21 and the seventh zone ECU 27are connected by a CAN-FD cable CB7.

In the present embodiment, the network formed by signal transmissionpaths between the central processing unit 10 and the zone ECUs 2 andsignal transmission paths between the zone ECUs 2 is referred to as“trunk network”. In FIG. 1, the trunk network includes the Ethernetcables EB1 to EB5 and the CAN-FD cables CB5 to CB5. Referring to FIG. 1,in the trunk network, the transmission path of the Ethernet signal (asignal conforming to the Ethernet standard) is indicated by a thicksolid line, and the transmission path of the CAN-FD signal or the CANsignal is indicated by a middle thick solid line. Furthermore, thesignal transmission path from each of the zone ECUs 21 to 27 to thein-vehicle device side is referred to as “device-side network”. In FIG.1, the signal path from each of the zone ECUs 21 to 27 to eachin-vehicle device, that is, the device-side network is indicated by athin solid line. The signal paths indicated by thin solid lines includeanalog/digital signal paths, CAN signal paths, LIN signal paths, andCAN-FD signal paths.

In order to enable autonomous driving and assisted driving of thevehicle 1, the central processing unit 10 calculates a route on whichthe vehicle 1 should travel in response to outputs from sensors mountedon the vehicle 1, and determines the motion of the vehicle 1 forfollowing the route. The central processing unit 10 is, for example, aprocessor including one or a plurality of chips, and has an artificialintelligence (AI) function in some cases. The sensors that outputinformation to the central processing unit 10 include, for example, acamera that captures an environment outside the vehicle, a radar thatdetects a target or the like outside the vehicle, a global positioningsystem (GPS) sensor that detects a position of the vehicle 1, a vehiclestate sensor that detects a behavior of the vehicle such as a vehiclespeed, an acceleration, and a yaw rate, and an occupant state sensorthat acquires a state of an occupant of the vehicle such as anin-vehicle camera. Furthermore, communication information from othervehicles located around an own vehicle and/or traffic information from anavigation system can be input to the central processing unit 10.

FIG. 2 is a diagram illustrating a functional configuration example ofthe first zone ECU 21.

The first zone ECU 21 includes a communication unit 120, a protocolconversion unit 140, and a signal conversion unit 150. The protocolconversion unit 140 includes a CAN conversion unit 141 and a LINconversion unit 142. The signal conversion unit 150 includes a digitalinput circuit 151, an analog input circuit 152, and control outputcircuits 153 and 154.

The first zone ECU 21 includes, as communication ports (hereinafter,referred to as “trunk ports”) connected to the trunk network, a trunkport 101 to which the Ethernet cable EB1 is connected and a trunk port102 to which the CAN-FD cable CB5 is connected. In other words, thetrunk port 101 and the trunk port 102 are ports to which a trunk networksignal that is a signal transmitted on the trunk network is input andoutput.

The first zone ECU 21 includes communication ports 111 to 118 ascommunication ports connected to the device-side network. The first zoneECU 21 inputs and outputs CAN signals via the communication ports 111 to113, inputs and outputs LIN signals via the communication port 114,inputs digital control signals via the communication port 115, inputsanalog control signals via the communication port 116, and outputsanalog control signals via the communication ports 117 and 118. Forexample, the communication port 111 is connected to a smart ECU 161, andthe smart ECU 161 is connected to an airbag device D11. For example, thecommunication port 112 is connected to a smart actuator 162 for lockingand unlocking a side door. For example, the communication port 113 isconnected to a smart actuator 163 for emitting a buzzer sound or thelike. For example, the communication port 114 is connected to a sensor164 (hereinafter, referred to as “keyless sensor 164”) for operating akeyless device. For example, the communication port 115 is connected toa switch 165 (for example, a clutch cut switch, a brake switch, or thelike). For example, the communication port 116 is connected to a sensor166 (for example, an accelerator pedal sensor, a clutch stroke sensor,or the like). For example, the communication port 117 is connected to aturn lamp 167 of a door mirror. For example, the communication port 118is connected to an actuator 168 (for example, an indicator lamp or thelike attached to a horn, a keyless buzzer, a meter device, or the like).Note that, in the drawings, the symbol mark of a lock mechanism isillustrated in addition to the smart actuator 162 for easy understandingof the description. Furthermore, in addition to the smart actuator 163,the symbol mark of a sound source mechanism is illustrated.

Although not specifically illustrated, the in-vehicle device can beattached or detached by inserting a connector at the distal end of acable extending from the in-vehicle device into each of thecommunication ports 111 to 118. In addition, each of the communicationports 111 to 118 can be connected to a smart connector (notillustrated), and the in-vehicle device can be attached to the smartconnector. The smart connector includes, for example, an analog/digitalconversion circuit, a driver circuit, and the like, and has a functionof transmitting a drive signal to an actuator serving as the in-vehicledevice, and/or a function of transmitting an input signal from a sensorserving as the in-vehicle device to the zone ECU 2.

The communication unit 120 includes a first transmission and receptionunit 121 connected to the trunk port 101, a second transmission andreception unit 122 connected to the trunk port 102, and a networkmanagement unit 123.

The first transmission and reception unit 121 has a function oftransmitting and receiving a trunk network signal (an Ethernet signal)to and from the central processing unit 10 via the trunk port 101 andthe Ethernet cable EB1. Although not specifically illustrated, the firsttransmission and reception unit 121 includes, for example, a codingcircuit that generates an Ethernet signal, a driver circuit that outputsthe Ethernet signal generated by the coding circuit to the centralprocessing unit 10, a receiver circuit that receives the Ethernet signaloutput from the central processing unit 10, and a decoding circuit thatdecodes the Ethernet signal received by the receiver circuit.

The second transmission and reception unit 122 has a function oftransmitting and receiving a trunk network signal (a CAN-FD signal) toand from the fifth zone ECU 25 via the trunk port 102 and the CAN-FDcable CB5. Although not specifically illustrated, the secondtransmission and reception unit 122 includes, for example, a codingcircuit that generates a CAN-FD signal, a driver circuit that outputsthe Ethernet signal generated by the coding circuit to the fifth zoneECU 25, a receiver circuit that receives the CAN-FD signal output fromthe fifth zone ECU 25, and a decoding circuit that decodes the CAN-FDsignal received by the receiver circuit.

The network management unit 123 has (a) a relay function of relaying atrunk network signal on a trunk network, that is, between the trunkports 101 and 102, (b) a distribution function of extracting a signalfor a device connected to the own ECU from trunk network signals anddistributing the signal, and (c) an integration function of integratingdata to be transmitted from the device connected to the own ECU to thecentral processing unit 10 and/or another zone ECU 2. Note that, in thefollowing description (including description of other zone ECUs 2), thefunctions mentioned above may be simply referred to as “(a) relayfunction”, “(b) distribution function”, and “(c) integration function”.

The protocol conversion unit 140 performs protocol conversion so thatdata can be exchanged between communication schemes. Specifically, theprotocol conversion unit 140 is connected to the network management unit123, and performs protocol conversion according to each of “(a) relayfunction”, “(b) distribution function”, and “(c) integration function”of the network management unit 123 described above. Note that, in thepresent embodiment, the protocol conversion includes a conversionprocess such as data length conversion between CAN and CAN-FD.

In “(a) relay function”, the network management unit 123 extracts data(hereinafter, referred to as “relay data”) to be transmitted to thefifth zone ECU 25 from the Ethernet signal input from the centralprocessing unit 10, and outputs the extracted data to the protocolconversion unit 140. The protocol conversion unit 140 converts relaydata to CAN protocol data and outputs the CAN protocol data to thenetwork management unit 123. The network management unit 123 generates aCAN signal on the basis of the CAN protocol data. The secondtransmission and reception unit 122 then outputs the CAN signal to thefifth zone ECU 25 via the trunk port 102. Similarly, the networkmanagement unit 123 extracts data (hereinafter, referred to as “relaydata”) to be transmitted to the central processing unit 10 from theCAN-FD signal input from the fifth zone ECU 25, and outputs theextracted data to the protocol conversion unit 140. The protocolconversion unit 140 converts the relay data to data in a formatconforming to the Ethernet protocol and outputs the data to the networkmanagement unit 123. The network management unit 123 generates anEthernet signal on the basis of the converted data. The firsttransmission and reception unit 121 then outputs the Ethernet signal tothe central processing unit 10 via the trunk port 101.

To summarize the above from the viewpoint of a delay time, at least areception delay time, a protocol conversion time, and a transmissiondelay time are generated in the process related to “(a) relay function”(hereinafter, referred to as “relay process”). The reception delay timeis a reception delay time due to a reception process in thecommunication unit 120. The reception delay time includes, for example,a reception processing time of a physical layer or the like in the firsttransmission and reception unit 121 or the second transmission andreception unit 122 and a subsequent decoding processing time, and anextraction processing time for extracting relay data in the networkmanagement unit 123. The protocol conversion time includes a time forprotocol conversion between communication schemes in the protocolconversion unit 140. The transmission delay time is a delay time due toa transmission process of transmitting protocol-converted data from thecommunication unit 120. The transmission delay time includes, forexample, the coding processing time in the first transmission andreception unit 121 or the second transmission and reception unit 122 andthe transmission processing time of the physical layer or the like.

In addition, the activation delay time related to an activationoperation and/or a return operation may be generated in the first zoneECU 21. For example, in “(a) relay function”, it is assumed that anactivation signal is transmitted from the Ethernet cable EB1 or theCAN-FD cable CB5. In a case where the phase locked loop (PLL) circuit ofthe communication unit 120 is in a stopped state when the activationsignal is received, for example, the activation and stabilization timeof the physical layer and the communication establishment time requiredfor establishing communication with the adjacent central processing unit10 and/or zone ECU 2 are generated as the activation delay time.Examples of the state where the PLL circuit of the communication unit120 is stopped include a power-off state and/or a sleep state of thefirst zone ECU 21.

In “(b) distribution function”, the network management unit 123 extractsdata (hereinafter, referred to as “own ECU data”) for a device connectedto the own ECU from the Ethernet signal input from the centralprocessing unit 10. The network management unit 123 determines whetherthe data for the own ECU is data for a device connected to the protocolconversion unit 140 or data for a device connected to the signalconversion unit 150, and distributes the data to each of the units. Inthe protocol conversion unit 140, when data for devices connected to thecommunication ports 111 to 113 is received from the network managementunit 123, the CAN conversion unit 141 converts the received data to asignal conforming to the CAN protocol and outputs the signal to thecommunication ports 111 to 113. As a result, a signal (for example, acontrol signal) from the central processing unit is transmitted to eachof the smart ECU 161 and the smart actuators 162 and 163. In the signalconversion unit 150, when data for controlling the turn lamp 167connected to the communication port 117 is received from the networkmanagement unit 123, the control output circuit 153 generates, forexample, an analog control signal of the turn lamp 167 according to acontrol value received from the central processing unit 10, and outputsthe analog control signal to the communication port 117. Similarly, inthe signal conversion unit 150, when data for controlling the actuator168 connected to the communication port 118 is received from the networkmanagement unit 123, the control output circuit 154 generates, forexample, an analog control signal of the actuator 163 according to acontrol value received from the central processing unit 10, and outputsthe analog control signal to the communication port 118. Note that, theprocess similar to that in the case of the central processing unit 10described above is also performed in a case where data for a deviceconnected to the own ECU is included in the CAN signal input from thefifth zone ECU 25.

To summarize the above from the viewpoint of the delay time, at leastthe reception delay time, the protocol conversion time, and a processingdelay time are generated in the process related to “(b) distributionfunction” (hereinafter, referred to as “distribution process”) in thecase of passing through the protocol conversion unit 140. Furthermore,in the case of passing through the signal conversion unit 150, at leastthe reception delay time due to the reception process in thecommunication unit 120 and the processing delay time in the signalconversion unit 150 are generated in the distribution process. Thereception delay time is a delay time due to the reception process in thecommunication unit 120 and includes, for example, the receptionprocessing time, the decoding processing time, and the extractionprocessing time for extracting data for the own ECU in the networkmanagement unit 123, as in the case of the relay process. The protocolconversion time includes a time for protocol conversion betweencommunication schemes in the protocol conversion unit 140. Theprocessing delay time includes a processing delay time in the smart ECU161 or the smart actuators 162 and 163.

Furthermore, in “(b) distribution function” of the first zone ECU 21, ina case where the in-vehicle device connected to the first zone ECU 21 isin a power-off state or a sleep state, an activation delay time forreturning the in-vehicle device is generated in addition to or insteadof the activation delay time described in “(a) relay function”.

In “(c) integration function”, for example, the protocol conversion unit140 receives an unlock or lock signal (a LIN signal) from the keylesssensor 164, converts data conforming to the LIN protocol to dataconforming to the Ethernet protocol, and transmits the converted data tothe network management unit 123. Furthermore, for example, in the signalconversion unit 150, the digital input circuit 151 receives an inputsignal from the switch 165, the analog input circuit 152 receives aninput signal from the sensor 166, and the circuits 151 and 152 transmitthe received data to the network management unit 123. The networkmanagement unit 123 integrates the received data from the protocolconversion unit 140 and the received data from the signal conversionunit 150. The first transmission and reception unit 121 outputs the dataintegrated by the network management unit 123, as an Ethernet signal, tothe central processing unit 10 via the trunk port 101. Note that, theprocess similar to that in the case of outputting the data to thecentral processing unit 10 is also performed in the case of transmittingthe data integrated by the integration function to the fifth zone ECU25.

Furthermore, for example, in a case where the first zone ECU 21 is inthe power-off state or the sleep state when the protocol conversion unit140 receives an output signal (a LIN signal) from the keyless sensor164, the return operation of the communication unit 120 is performed inthe first zone ECU 21. In addition, the communication unit 120transmits, to the central processing unit 10 and/or the fifth zone ECU25, the reception of the unlock (lock) signal from the keyless sensor164 after the return operation is completed. The transmission signal hasa function as a return signal for causing the central processing unit 10and/or the fifth zone ECU 25 to perform the return operation.

To summarize the above from the viewpoint of the delay time, at leastthe protocol conversion time, an integration processing time, and thetransmission delay time are generated in the process related to “(c)integration function” (hereinafter, referred to as “integrationprocess”) in the case of passing through the protocol conversion unit140. In addition, at least the integration processing time and thetransmission delay time are generated in the integration process in thecase of passing through the signal conversion unit 150. The protocolconversion time includes the time for protocol conversion betweencommunication schemes in the protocol conversion unit 140. Theintegration processing time includes a time for the network managementunit 123 to integrate the data received from the signal conversion unit150 and/or the protocol conversion unit 140 for each transmissiondestination. The transmission delay time is a delay time due to atransmission process of transmitting the data integrated by the networkmanagement unit 123 from the communication unit 120. The transmissiondelay time includes, for example, the coding processing time in thefirst transmission and reception unit 121 or the second transmission andreception unit 122 and the transmission processing time of the physicallayer or the like.

Furthermore, in “(c) integration function” of the first zone ECU 21, ina case where a return signal (for example, an unlock signal for thekeyless sensor 164) is received from a predetermined in-vehicle deviceconnected to the first zone ECU 21, the activation delay time fortransmitting the return signal to the central processing unit 10 or thefifth zone ECU 25 is generated. In a case where the PLL circuit of thecommunication unit 120 is stopped, for example, the activation andstabilization time of the physical layer and the communicationestablishment time required for establishing communication with theadjacent central processing unit 10 and/or zone ECU 2 are generated asthe activation delay time. In addition, the activation delay time mayinclude a return processing time in the network management unit 123.

FIG. 3 illustrates a functional configuration example of the third zoneECU 23. Here, the description of the same configuration as that of thefirst zone ECU 21 may be omitted.

The third zone ECU 23 includes a communication unit 320, a protocolconversion unit. 340, and a signal conversion unit 350. The protocolconversion unit 340 includes a CAN conversion unit 341. The signalconversion unit 350 includes a digital input circuit 351, an analoginput circuit 352, and a control output circuit 353.

The third zone ECU 23 includes a trunk port 301 to which the Ethernetcable EB3 is connected and a trunk port 302 to which the Ethernet cableEB5 is connected. In other words, the trunk port 301 and the trunk port302 are ports to which a trunk network signal is input and output.

The third zone ECU 23 includes communication ports 311 to 315 as deviceports. The third zone ECU 23 inputs and outputs CAN signals via thecommunication ports 311 and 312, inputs digital control signals via thecommunication port 313, inputs analog control signals via thecommunication port 314, and outputs analog control signals via thecommunication port 315. For example, the communication port 311 isconnected to a collision detection unit 361 that detects a collision ofthe vehicle 1. For example, the communication port 312 is connected to asmart actuator 362 for operating a turn lamp on the vehicle front side.For example, the communication port 313 is connected to a switch 363(for example, a washer level switch, a hood switch, or the like). Forexample, the communication port 314 is connected to a sensor 364 (forexample, an outside air temperature sensor, an air flow sensor, or thelike). For example, the communication port 315 is connected to anactuator 365 (for example, a horn, a keyless buzzer, or the like). Notethat, in the drawings, the symbol mark of the turn lamp is illustratedin addition to the smart actuator 362 for easy understanding of thedescription.

The communication unit 320 includes a third transmission and receptionunit 321 connected to the trunk port 301, a fourth transmission andreception unit 322 connected to the trunk port 302, and a networkmanagement unit 323. Note that, in the communication unit 320, theconfiguration and function related to the invention of the presentapplication are similar to those of the communication unit 120 of thefirst zone ECU 21 described above, and thus the detailed descriptionthereof will be omitted here. Specifically, when the communication unit120 of the first zone ECU 21 is compared with the communication unit 320of the third zone ECU 23, the second transmission and reception unit 122of the first zone ECU 21 conforms to the CAN-FD protocol, whereas thefourth transmission and reception unit 322 of the third zone ECU 23conforms to the Ethernet protocol. However, the configuration of thetransmission and reception circuit and the delay information conformingto each communication scheme can be replaced on the basis of theconventional technique.

The protocol conversion unit 340 performs protocol conversion so thatdata can be exchanged between communication schemes. Here, thedifference between the protocol conversion unit 340 and the protocolconversion unit 140 of the first zone ECU 21 will be mainly described,and the description of the same contents may be omitted.

The third zone ECU 23 relays between an Ethernet signal and an Ethernetsignal in “(a) relay function”. Consequently, unlike the protocolconversion unit 140 described above, the protocol conversion unit 340does not require protocol conversion in the relay process. That is, inthe relay process of the third zone ECU 23, at least the reception delaytime and the transmission delay time are generated. In addition, theactivation delay time related to the activation operation and/or thereturn operation may be generated in the third zone ECU 23. Note thatthe reception delay time, the transmission delay time, and theactivation delay time are similar to those of the first zone ECU 21described above, and thus the detailed description thereof will beomitted here.

“(b) Distribution function” and the delay time due to the distributionprocess in the third zone ECU 23 have the same contents as those in thefirst zone ECU 21 described above, and thus the detailed descriptionthereof will be omitted here. To summarize the above from the viewpointof the delay time, at least the reception delay time, the protocolconversion time, and the processing delay time are generated in thedistribution process of the third ECU 23 (1) in the case of passingthrough the protocol conversion unit 340. Furthermore, (2) in the caseof passing through the signal conversion unit 350, at least thereception delay time due to the reception process in the communicationunit 320 and the processing delay time in the signal conversion unit 350are generated. In addition, in a case where the in-vehicle deviceconnected to the third zone ECU 23 is in the power-off state or thesleep state, the activation delay time for returning the in-vehicledevice may be generated in the activation operation and the returnoperation described above. Note that the reception delay time, theprotocol conversion time, the processing delay time, and the activationdelay time are similar to those of the first zone ECU 21 describedabove, and thus the detailed description thereof will be omitted here.

“(c) Integration function” and the delay time due to the integrationprocess in the third zone ECU 23 have the same contents as those in thefirst zone ECU 21 described above, and thus the detailed descriptionthereof will be omitted here. To summarize the above from the viewpointof the delay time, at least the protocol conversion time, theintegration processing time, and the transmission delay time aregenerated in the integration process of the third ECU 23 (1) in the caseof passing through the protocol conversion unit 340. In addition, atleast the integration processing time and the transmission delay timeare generated (2) in the case of passing through the signal conversionunit 350. Furthermore, in a case where a return signal is received froma predetermined in-vehicle device connected to the third zone ECU 23,the activation delay time for transmitting the return signal to thecentral processing unit 10 and/or the fourth zone ECU 24 may begenerated. Note that the protocol conversion time, the integrationprocessing time, the transmission delay time, and the activation delaytime are similar to those of the first zone ECU 21 described above, andthus the detailed description thereof will be omitted here.

FIG. 4 illustrates a functional configuration example of the fifth zoneECU 25. Here, the description of the same configuration as that of thefirst zone ECU 21 and/or the third zone ECU 23 may be omitted.

The fifth zone ECU 25 includes a communication unit 520, a protocolconversion unit 540, and a signal conversion unit 550. The protocolconversion unit 540 includes a CAN conversion unit 541 and a LINconversion unit 542. The signal conversion unit 550 includes a digitalinput circuit 551, an analog input circuit 552, and a control outputcircuit 553.

The fifth zone ECU 25 includes a trunk port 501 to which the CAN-FDcable CB5 is connected and a trunk port 502 to which the CAN-FD cableCB8 is connected. In other words, in the fifth zone ECU 25, a CAN-FDsignal is input and output to and from the trunk port 501 and the trunkport 502, and the trunk port 501 and the trunk port 502 are directlyconnected.

The fifth zone ECU 25 includes communication ports 511 to 516 as deviceports. The fifth zone ECU 25 inputs and outputs CAN signals via thecommunication ports 511 and 512, inputs and outputs LIN signals via thecommunication port 513, inputs digital control signals via thecommunication port 514, inputs analog control signals via thecommunication port 515, and outputs analog control signals via thecommunication port 516. For example, the communication port 511 isconnected to a smart actuator 561 for emitting a buzzer sound or thelike. For example, the communication port 512 is connected to a smartactuator 562 for locking a side door. For example, the communicationport 513 is connected to a back sonar device 563. For example, thecommunication port 514 is connected to a switch 564. For example, thecommunication port 515 is connected to a sensor 565 (for example, a fuelsensor, a kick sensor, or the like). For example, the communication port516 is connected to a turn light 566 on the rear left of the vehicle.Note that, in the drawings, the symbol mark of the sound sourcemechanism is illustrated in addition to the smart actuator 561 for easyunderstanding of the description. Furthermore, in addition to the smartactuator 562, the symbol mark of the lock mechanism is illustrated.

The communication unit 520 includes a transmission and reception unit521 connected to a common communication line connecting the trunk port501 and the trunk port 502 and a network management unit 522. Althoughnot specifically illustrated, the transmission and reception unit 521includes, for example, a coding circuit that generates a CAN-FD signal,a driver circuit and a receiver circuit connected to the commoncommunication line, and a decoding circuit that decodes the CAN-FDsignal received by the receiver circuit.

The protocol conversion unit 540 performs protocol conversion so thatdata can be exchanged between communication schemes. Here, thedifference between the protocol conversion unit 540 and the protocolconversion unit 140 of the first zone ECU 21 will be mainly described,and the description of the same contents may be omitted.

In the fifth zone ECU 25, since the trunk port 501 and the trunk port502 are directly connected, there is no concept of “(a) relay function”.That is, in the fifth zone ECU 25, the relay process of relaying betweentwo adjacent zone ECUs 2 is not performed, and the delay time betweenthe trunk port 501 and the trunk port 502 is only the signal propagationtime of the common communication line and is extremely small. Similarly,the activation delay time is not generated in “(a) relay function” ofthe fifth zone ECU 25.

“(b) Distribution function” and the delay time due to the distributionprocess in the fifth zone ECU 25 have the same contents as those in thefirst zone ECU 21 described above, and thus the detailed descriptionthereof will be omitted here. To summarize the above from the viewpointof the delay time, at least the reception delay time, the protocolconversion time, and the processing delay time are generated in thedistribution process of the fifth ECU 25 (1) in the case of passingthrough the protocol conversion unit 540. Furthermore, (2) in the caseof passing through the signal conversion unit 550, at least thereception delay time due to the reception process in the communicationunit 520 and the processing delay time in the signal conversion unit 550are generated. In addition, in a case where the in-vehicle deviceconnected to the fifth zone ECU 25 is in the power-off state or thesleep state, the activation delay time for returning the in-vehicledevice may be generated in the activation operation and the returnoperation described above. Note that the reception delay time, theprotocol conversion time, the processing delay time, and the activationdelay time are similar to those of the first zone ECU 21 describedabove, and thus the detailed description thereof will be omitted here.

“(c) Integration function” and the delay time due to the integrationprocess in the fifth zone ECU 25 have the same contents as those in thefirst zone ECU 21 described above, and thus the detailed descriptionthereof will be omitted here. To summarize the above from the viewpointof the delay time, at least the protocol conversion time, theintegration processing time, and the transmission delay time aregenerated in the integration process of the fifth ECU 25 (1) in the caseof passing through the protocol conversion unit 540. In addition, atleast the integration processing time and the transmission delay timeare generated (2) in the case of passing through the signal conversionunit 550. Furthermore, in a case where a return signal is received froma predetermined in-vehicle device connected to the fifth zone ECU 25,the activation delay time for transmitting the return signal to thefirst zone ECU 21 and/or the sixth zone ECU 26 may be generated. Notethat the protocol conversion time, the integration processing time, thetransmission delay time, and the activation delay time are similar tothose of the first zone ECU 21 described above, and thus the detaileddescription thereof will be omitted here.

<Design Method for Vehicle Control System>

—Outline—

As described in “Technical Problem”, in the future, the arithmeticprocessing function and the control function of each actuator will beintegrated into a central processing unit that integrally manages theoperation of the entire vehicle. This means that the arithmetic functionand the control function currently mounted on an ECU provided for eachzone of the vehicle and an ECU (hereinafter, collectively referred to as“conventional ECU”) provided for each function as in Patent Literature 1are incorporated in the central processing unit.

Consequently, the inventors of the present application have extensivelyconducted studies, and have found a design method for incorporating morefunctions and reducing design man-hours as much as possible when thearithmetic function and the control function mounted on the conventionalECU are incorporated in the central processing unit.

The outline of the design method according to the present disclosurewill be briefly described. In a case where the control function thatoperates without any problem by a control method using the conventionalECU is incorporated in the central processing unit, there is a problemof communication delay as one of elements largely different from theconventional ECU. As described above, it is not realistic to directlyconnect each sensor and each actuator to the central processing unit inwhich functions are integrated, because the number of signal linesincreases, and thus the in-vehicle network is assumed to be constructed.Then, a relay device such as a network hub device and/or a gatewaydevice is interposed between the central processing unit and anin-vehicle device or an ECU that controls the in-vehicle device,resulting in a communication delay. As a result, this communicationdelay may become a problem in control that requires a response speedfrom the occurrence of a certain input and/or situation to the actualoperation of the in-vehicle device.

In particular, in a case where functions are integrated in the centralprocessing unit, it is necessary to implement high-speed andlarge-capacity data transmission, and for this purpose, high-speedinterface technology is needed to be applied. In general, in thehigh-speed interface technology, it is necessary to provide a physicallayer for exchanging high-speed signals, and the activation time on theorder of several tens of milliseconds is required to activate thephysical layer. Furthermore, it is assumed in the in-vehicle networkthat, for example, a plurality of communication protocols such as CAN,CAN-FD, and/or Ethernet are mixed and in-vehicle devices (including zoneECUs) corresponding to different communication protocols are connectedin a daisy chain layout.

Therefore, the invention of the present application is characterized inthat, in particular, an activation time and/or a return time(hereinafter, simply referred to as “activation time”) is focused on,“allowable delay time” is set as a reference of an activation delay timeallowed as the activation time, and the connection location of thein-vehicle device is set on the basis of the allowable delay time.Alternatively, the invention of the present application is characterizedin that “allowable delay time” mentioned above is set, and a daisy chainnetwork path is configured on the basis of the allowable delay time. Theactivation delay time includes an activation delay time (hereinafter,referred to as “input-side activation delay time”) from an in-vehicledevice (including a zone ECU) to which an input that is the source ofcontrol such as a signal is made to the central processing unit 10, andan activation delay time (hereinafter, referred to as “output-sidecommunication delay time”) from the central processing unit 10 to acontrol circuit (including a zone ECU) on the side of an in-vehicledevice operated in response to the input.

That is, the invention of the present application is characterized inthat the connection location of the in-vehicle device is set and/or thedaisy chain network path is configured on the basis of the relationshipbetween the input-side activation delay time and the output-sideactivation delay time, and the allowable delay time. Here, “allowabledelay time” is a time that can be freely set, and is not particularlylimited. For example, the allowable delay time can be set on the basisof standards such as vehicle safety standards, or can be set on thebasis of a behavior of the vehicle, relevance to other functions, or thelike. Alternatively, the allowable delay time can be set from theviewpoint of not giving discomfort or stress to the driver or the like.

Here, in the present embodiment, as illustrated in FIG. 1, the vehicle 1is divided into a plurality of (seven in the present embodiment) zones,the zone ECU 2 is provided in each zone, and these zones are connectedto construct a trunk network. Each zone ECU 2 includes a communicationport, and the communication port is connected to an in-vehicle device.With such a configuration, it is easy to recognize the activation delaytime between the central processing unit 10 and each communication portin advance. That is, the communication delay time with the centralprocessing unit 10 can be estimated for each communication port beforethe in-vehicle device is connected to each communication port of thezone ECU 2. As a result, it is possible to relatively easily set theconnection location of the in-vehicle device and/or configure the daisychain network path without performing complicated arithmetic processing.

—Design Flow of Vehicle Control System—

Hereinafter, a specific design flow of the design method for a vehiclecontrol system according to the present embodiment will be describedwith reference to FIGS. 5 to 10. Note that, it can be configured that,for example, a design program for implementing the present design methodis prepared, and the design program is executed using a computer.

Referring to FIG. 5, in step S1, a network serving as a base of anin-vehicle network is constructed. For example, a trunk networkindicated by thick lines and medium thick lines in FIG. 6 is constructedfirst. Thereafter, a sub-network from each zone ECU 2 having a functionas a network hub device in the trunk network is configured, so that thein-vehicle network spreading in a daisy chain layout from the centralprocessing unit 10 is configured. Note that, in the embodiment, thedescription of the sub-network is omitted in order to avoid complicationof the description. The daisy chain network is a network in which aplurality of devices (here, the central processing unit 10 and theplurality of zone ECUs 2) are connected in a row, collectively connectedin a ring shape, or connected in a combination of the row and the ringshape.

In step S2, the connection destination of an in-vehicle device to becontrolled (referred to as “operating device”) is set. The reference ofthe connection destination of the operating device is not particularlylimited. For example, the operating device is preferentially connectedto, as a first connection destination, the zone ECU 2 installed at aposition closest to the position where the operating device is disposedor an ECU (including a smart ECU) connected to the sub-network of thezone ECU 2.

In step S3, the connection destination of an information acquisitionunit (for example, a sensor, a switch, or the like described above) isset. The reference of the connection destination of the informationacquisition unit is not particularly limited. For example, theinformation acquisition unit is preferentially connected to, as a firstconnection destination, the zone ECU 2 installed at a position closestto the position where the information acquisition unit is disposed or anECU (including a smart ECU) connected to the sub-network of the zone ECU2.

In step S4, the activation time of each communication path is calculatedfirst. Specifically, the communication path between the informationacquisition unit such as a sensor or a switch and the operating deviceis specified.

FIG. 7 is obtained by extracting a network related to the keyless sensor164 and the smart actuators 162 and 562 for locking and unlocking doorsfrom the configuration of FIG. 6. FIG. 7 illustrates a case where“information acquisition unit” is the keyless sensor 164 that acquiresinformation from a vehicle remote controller 80, and “operating device”is the smart actuators 162 and 562 for locking and unlocking doors.

In the case of the example illustrated in FIG. 7, a path from thekeyless sensor 164 through the first zone ECU 21 via a LIN signal lineto the central processing unit 10 via the Ethernet cable EB1 isspecified as an input-side communication path. In addition, in the caseof the example illustrated in FIG. 7, since four smart actuators 162 and562 for locking and unlocking doors are mounted, four output-sidecommunication paths are specified.

Specifically, a path from the central processing unit 10 through thefirst zone ECU 21 via the Ethernet cable EB1 to the smart actuator 162via a CAN signal line CS15 is specified as a first output-sidecommunication path. A path from the central processing unit 10 throughthe first zone ECU 21 via the Ethernet cable EB1, through the seventhzone ECU 27 via an Ethernet cable EB51, through the fifth zone ECU 25via a CAN-FD cable CB52 to the smart actuator 562 via a CAN signal lineCS51 is specified as a second output-side communication path. A pathfrom the central processing unit 10 through the second zone ECU 22 viathe Ethernet cable EB2 to the smart actuator 162 via a CAN signal lineCS22 is specified as a third output-side communication path. A path fromthe central processing unit 10 through the second zone ECU 22 via theEthernet cable EB2, through the sixth zone ECU 26 via the CAN-FD cableCB6 to the smart actuator 562 via a CAN signal line CS61 is specified asa fourth output-side communication path.

Next, the activation delay time in each communication path iscalculated. For example, the activation delay time (corresponding to afirst activation time) from when the network from the first zone ECU 21to the central processing unit 10 is activated to when the centralprocessing unit 10 is activated is calculated in the input-sidecommunication path. In calculating the activation delay time, specificarithmetic processing such as simulation in which various parameters areset can be performed, or simple arithmetic processing can be performedusing data registered in a database (denoted as “DB” in FIG. 5) inadvance. The calculation of the activation delay time is repeated untilthe arithmetic processing in the input-side communication path and theoutput-side communication path is completed.

Specifically, the activation delay time (corresponding to a secondactivation time) from when the network from the central processing unit10 to the first zone ECU 21 is activated to when the first zone ECU 21is activated is calculated in the first output-side communication path.Similarly, the activation delay time (corresponding to the secondactivation time) from when the first zone ECU 21 and the seventh zoneECU 27 constituting the network from the central processing unit 10 tothe fifth zone ECU 25 are sequentially activated to when the fifth zoneECU 25 is activated is calculated in the second output-sidecommunication path. The activation delay time is similarly calculated inthe third and fourth output-side communication paths. Note that in FIG.5, the calculation of the activation delay time in each communicationpath can be performed in parallel or simultaneously.

FIGS. 8 and 9 are diagrams for explaining the activation delay time, andillustrate, as an example, a flow from the input of operationinformation for locking and unlocking from the remote controller to thekeyless sensor 164 to the locking and unlocking of a door by the smartactuator 162 connected to the second zone ECU 22.

As illustrated in FIGS. 8 and 9, for example, when an unlockingoperation signal is input to the keyless sensor 164, an activation andtransmission signal process is performed in the keyless sensor 164, andthe unlocking operation signal is output to the first zone ECU 21. Theunlocking operation signal is an example of an activation signal.

For example, the activation time of a transmission circuit thattransmits an unlocking operation signal and a transmission delay timedue to the transmission signal processing are generated as theactivation delay time t1 in the keyless sensor 164 t12 is acommunication delay time (corresponding to the activation delay time) inthe communication path (the LIN signal line CS13) between the keylesssensor 164 and the first zone ECU 21.

Since “relay process” described above is performed in the first zone ECU21, an activation time of the communication unit 120, a reception delaytime due to a reception process, and a transmission delay time due to atransmission process to the central processing unit 10 are generated asthe activation delay time t13. t14 is a communication delay time(corresponding to the activation delay time) in the communication path(the Ethernet cable EB1) between the first zone ECU 21 and the centralprocessing unit 10.

In the central processing unit 10, an activation time of the centralprocessing unit 10, a reception processing time related to reception ofan Ethernet signal from the first zone ECU 21, and a receptionprocessing time related to transmission of the Ethernet signal to thefirst zone ECU 21 and the second zone ECU 22 are generated as anactivation delay time t15. The activation time of the central processingunit 10 includes, for example, an activation time of a physical layer(not illustrated) such as a PLL. The transmission delay time includes,for example, a coding processing time and a transmission processing timeof a physical layer or the like. The reception delay time includes, forexample, a reception processing time of a physical layer or the like anda subsequent decoding processing time. Note that the central processingunit 10 performs a failure determination process and a control operationdetermination process (including a fail-safe process). Although thesefailure determination process and control operation determinationprocess are not included in the communication delay time, for example,in a case where it takes more time for each process than theconventional ECU if these processes are incorporated in the centralprocessing unit 10, the processing time can be included in theactivation delay time. t16 is a communication delay time (correspondingto the activation delay time) in the communication path (the Ethernetcable EB2) between the central processing unit 10 and the second zoneECU 22.

Since “relay process” described above is performed in the second zoneECU 22, an activation time of a communication unit (corresponding to thecommunication unit 120 of the first zone ECU 21), the reception delaytime due to the reception process, a protocol conversion time of aprotocol conversion unit (corresponding to the protocol conversion unit140 of the first zone ECU 21), and the transmission delay time due tothe transmission process to the central processing unit 10 are generatedas the activation delay time t17. t18 is a communication delay time(corresponding to the activation delay time) in the communication path(the CAN signal line CS22) between the second zone ECU 22 and the smartactuator 162.

When the smart actuator 162 receives an unlocking operation signal fromthe second zone ECU 22, a door is unlocked. In a case where anyactivation delay time t19 is generated in the process from when theunlocking operation signal is output from the second zone ECU 22 to whenthe smart actuator 162 unlocks a door, the activation delay time t19 canbe added to the calculation result of the activation delay times t11 tot18.

As described above, in step S4 of FIG. 5, an activation delay time T10from a time Ts when an unlocking operation signal is input to thekeyless sensor 164 to a time Tf when a control signal is output from thesmart actuator 162 is calculated. For example, the activation delay timeT10 from when operation information for locking or unlocking is inputfrom the remote controller to the keyless sensor 164 to when a door islocked or unlocked by the smart actuator 162 connected to the secondzone ECU 22 is the sum of the activation delay times t11 to t19.

In step S4 of FIG. 5, the activation delay time is calculated for allthe devices to be operated. For example, in the example of FIG. 7, theactivation delay time in a case where an operation signal is input tothe smart actuator 162 is calculated for each of the four smartactuators 162 and 562.

In the next step S5, the activation delay time T10 is compared with theallowable delay time of a door locking device. The allowable delay timeis, for example, a time allowed for the in-vehicle device to be operatedfrom when an activation signal is input to the information acquisitionunit to when the zone ECU or the output circuit to which the in-vehicledevice is connected outputs a control signal, and is set in advance ineach in-vehicle device, for example. For example, in the case of thedoor locking device, the allowable delay time corresponds to the timeallowed from when an operation signal is input from the remotecontroller 80 to the keyless sensor 164 to when a control signal isoutput to the smart actuators 162 and 562. In other words, theactivation delay time T10 is a minimum required activation delay time ina case where the information acquisition unit is connected to any one ofthe zone ECUs 2 and the in-vehicle device to be operated (hereinafter,also referred to as “operating device”) is connected to any one of thezone ECUs 2. Consequently, in step S5, the activation delay time T10 isset as a predetermined reference time, and the activation delay time T10is compared with the allowable delay time of the operating device.

Then, when the activation delay times of all the smart actuators 162 and562 are within the allowable delay time (YES in step S5), the designprocess for the smart actuators 162 and 562 ends.

On the other hand, when the activation delay times of the smartactuators 162 and 562 exceed the allowable delay time (NO in step S5),the flow proceeds to step S6.

In step S6, a design change portion is considered. For example, it isconsidered that the connection destination of the informationacquisition unit and/or the operating device is changed. In other words,the operation of determining the connection destination of theinformation acquisition unit and/or the connection destination of thein-vehicle device from the zone ECUs 2 such that the total time of thefirst activation time and the second activation time is less than thepredetermined delay time is performed. In the above example, the firstactivation time is a time from when an operation signal is input fromthe remote controller 80 to the keyless sensor 164 serving as theinformation acquisition unit to when the central processing unit 10 isactivated. In addition, the second activation time is a time from thecentral processing unit to when the zone ECU 2 to which the door lockingdevice serving as the operating device is connected or the controlcircuit of the door locking device is activated. For example, in thenetwork configuration of FIG. 7, in a case where the activation delaytime of the smart actuator 562 connected to the fifth zone ECU 25 is NG,it is possible to attempt to connect the smart actuator 562 connected tothe fifth zone ECU 25 to the first zone ECU 21. In a case where theconnection is changed, for example, the processes of steps S4 and S5 inFIG. 5 can be performed again.

Furthermore, for example, in the network configuration of FIG. 7, in acase where the activation delay time of the smart actuator 562 connectedto the fifth zone ECU 25 is NG, the network configuration can bechanged. For example, FIG. 10 (corresponding to the networkconfiguration of FIG. 1) illustrates an example in which the networkconfiguration is changed from that of FIG. 7. Specifically, according tothe example of FIG. 10, in the connection between the first zone ECU 21and the fifth zone ECU 25, the first zone ECU 21 and the fifth zone ECU25 are directly connected by the CAN-FD cable CB5 instead of theconfiguration of passing through the seventh zone ECU 27. In thismanner, the activation delay time can be shortened by reducing thenumber of zone ECUs interposed between the central processing unit 10and the zone ECU 2 or changing the communication protocol for connectingthe central processing unit 10 and the zone ECU 2. Note that, in thecase of changing the network configuration of FIG. 7 to the networkconfiguration of FIG. 10, the configuration of the trunk network ischanged. On the other hand, the trunk network is a base network, and ingeneral, a large number of networks (including daisy chain networks) arealso configured under the trunk network and thus it is preferable thatthe network underlying the zone ECU be changed first without changingthe trunk network.

As described above, according to the present embodiment, the firstactivation time from when each network from a predetermined zone ECU(hereinafter, referred to as “first zone ECU”) that receives anactivation signal from the information acquisition unit out of the zoneECUs 2 toward the central processing unit 10 is sequentially activatedto when the central processing unit 10 is activated is calculated. Inaddition, the second activation time from when each network toward apredetermined zone ECU (hereinafter, referred to as “second zone ECU”)that outputs a control signal to an in-vehicle device operating inresponse to an activation signal from the central processing unit issequentially activated to when the second zone ECU is activated iscalculated. The connection destination of the information acquisitionunit, the connection destination of the in-vehicle device, and/or thenetwork path are determined so that the total time of the firstactivation time and the second activation time is less than thepredetermined allowable delay time. Here, the network path includes anetwork path from the first zone ECU to the central processing unit 10and a network path from the central processing unit 10 to the secondzone ECU.

As a result, it is possible to configure an in-vehicle networkreflecting an activation delay in a complicated network system in whicha plurality of communication protocols are mixed and differentcommunication protocols are connected in a daisy chain layout.Furthermore, as in the above embodiments, by providing the allowabledelay time, the configuration of the in-vehicle network and theconnection destination of the in-vehicle device (including theinformation acquisition unit and the operating device) can be roughlydetermined before complicated arithmetic processing or the like isperformed. Note that, in the present disclosure, the zone ECU is aconcept including a smart ECU connected to the zone ECU 2 in addition tothe zone ECU 2 described in the above embodiment.

Furthermore, in the present embodiment, the vehicle 1 is divided into aplurality of (seven in the present embodiment) zones, the zone ECU 2 isprovided in each zone, and these zone ECUs 2 are connected to constructa trunk network. Each zone ECU 2 includes a communication port, and thecommunication port is connected to an in-vehicle device using aconnector or the like. As a result, the activation delay time betweeneach zone ECU 2 and the central processing unit 10 can be obtained inadvance by simulation or the like. As a result, in determining theconnection destination of the information acquisition unit and theconnection destination of the operating device, it is possible todetermine a zone ECU that is inappropriate as the connection destinationin advance, and the design efficiency can be improved.

Second Embodiment

Next, a design method of a second embodiment will be described withreference to FIGS. 11 to 14. Note that the configuration of anin-vehicle network system is the same as that of the first embodiment,and thus the detailed description thereof will be omitted here.

Note that, it can be configured that, for example, a design program forimplementing the present design method is prepared, and the designprogram is executed using a computer.

Referring to FIG. 11, in step S10, a communication path between anin-vehicle device on an input side (hereinafter, referred to as “inputdevice”) such as a sensor or a switch and an in-vehicle device to becontrolled (hereinafter, referred to as “operating device”) isspecified. For example, FIG. 12 illustrates a case where the inputdevice is the collision detection unit 361 and the operating device isthe airbag device D11. In the case of the example illustrated in FIG.12, in step S10, a path from the collision detection unit 361 throughthe third zone ECU 23 via a LIN signal line CS31 to the centralprocessing unit 10 via the Ethernet cable EB3 is specified as aninput-side communication path. In addition, a path from the centralprocessing unit 10 through the first zone ECU 21 via the Ethernet cableEB1 to the smart ECU 161 via a CAN signal line CS11 is specified as anoutput-side communication path.

In step S11, it is determined whether or not the communication protocolis converted in the specified communication path. In the example of FIG.12, there is no conversion of the communication protocol in theinput-side communication path, but since the conversion from theEthernet protocol to the CAN protocol is performed in the output-sidecommunication path, YES is determined, and the flow proceeds to the nextstep S15.

In steps S15 to S17, the communication delay time is estimated. Notethat, in FIG. 11, the communication delay time in steps S15 to S17 andthe control processing time in step S18 to be described later aredescribed separately for the sake of convenience, but steps S15 to S18can be performed in parallel or simultaneously.

FIGS. 13 and 14 are diagrams for explaining the communication delaytime, and illustrate a temporal flow from when a collision is detectedby the collision detection unit 361 to when a signal is output to theairbag device DI. The airbag device D11 is an example of an actuator tobe operated.

As illustrated in FIGS. 13 and 14, when collision information is inputto the collision detection unit 361, the collision detection unit 361performs transmission signal processing, and outputs a collisiondetection signal to the third zone ECU 23. The collision detection unit361 is an example of an information acquisition unit, and the collisiondetection signal output from the collision detection unit 361 is anexample of operation information.

The transmission delay time due to the transmission signal processing isgenerated as a communication delay time t1 in the collision detectionunit 361. The transmission delay time includes, for example, a codingprocessing time and a transmission processing time of a physical layeror the like. t12 is a communication delay time in the communication path(the LIN signal line CS31) between the collision detection unit 361 andthe third zone ECU 23.

Since “relay process” described above is performed in the third zone ECU23, a reception delay time due to a reception process and a transmissiondelay time due to a transmission process to the central processing unit10 are generated as a communication delay time t13. t14 is acommunication delay time in the communication path (the Ethernet cableEB3) between the third zone ECU 23 and the central processing unit 10.

In the central processing unit 10, a reception processing time relatedto reception of an Ethernet signal from the third zone ECU 23 and areception processing time related to transmission of the Ethernet signalto the first zone ECU 21 and the second zone ECU 22 are generated as acommunication delay time t15. The transmission delay time includes, forexample, a coding processing time and a transmission processing time ofa physical layer or the like. The reception delay time includes, forexample, a reception processing time of a physical layer or the like anda subsequent decoding processing time. Note that the central processingunit 10 performs a failure determination process and a control operationdetermination process (including a fail-safe process). Although thesefailure determination process and control operation determinationprocess are not included in the communication delay time, for example,in a case where it takes more time for each process than theconventional ECU if these processes are incorporated in the centralprocessing unit 10, the processing time can be included in thecommunication delay time in step S18. t16 is a communication delay timein the communication path (the Ethernet cable EB1) between the firstzone ECU 21 and the central processing unit 10.

Since “relay process” described above is performed in the first zone ECU21, the reception delay time due to the reception process, a protocolconversion time of the protocol conversion unit 140, and thetransmission delay time due to the transmission process to the centralprocessing unit 10 are generated as a communication delay time t17. t18is a communication delay time in the communication path (the CAN signalline CS11) between the first zone ECU 21 and the smart ECU 161.

The reception delay time due to the signal transmission process of thefirst zone ECU 21 is generated as a communication delay time t19 in thesmart ECU 161.

The reception delay time includes, for example, a reception processingtime of a physical layer or the like and a subsequent decodingprocessing time. Thereafter, a control signal of the airbag device D11is generated and output in the smart ECU 161.

As described above, in the flow of steps S15 to 318, a communicationdelay time T10 from a time Ts when a collision is detected by thecollision detection unit 361 to a time Tf when a control signal isoutput from the smart ECU 161 is calculated. As illustrated in FIG. 14,the communication delay time T10 in the example of FIG. 12 is the sum ofthe communication delay times t11 to t19.

In the next step S19, the communication delay time T10 is compared withthe allowable delay time of the airbag device D11. The allowable delaytime is a time allowed for the actuator to be operated from when theoperation information is input to the information acquisition unit towhen the control signal of the actuator is output, and is set in advancein each actuator, for example. For example, in the case of the airbagdevice, the allowable delay time corresponds to a time allowed from whena collision detection signal is output from the collision detection unit361 to when a control signal is output to the airbag device D11. Inother words, the communication delay time T10 is a minimum requireddelay time in a case where the input device is connected to one of thefirst zone ECU 21 and the third zone ECU 23 and the operating device isconnected to the other. Consequently, in step S19, the communicationdelay time T10 is set as a predetermined reference time, and thecommunication delay time T10 is compared with the allowable delay timeof the airbag device D11.

Then, when the allowable delay time of the airbag device D11 is lessthan the predetermined reference time (the communication delay time T10)(YES in step S19), the flow proceeds to step 320, and it is determinedthat an operation-signal generation unit of the airbag device D11 cannotbe incorporated in the central processing unit 10. In step S20, forexample, the operation-signal generation unit of the airbag device D11is designed to be provided in the first zone ECU 21 or the smart ECU161. Furthermore, in step S20, the connection of the operation-signalgeneration unit in the zone ECU 2 other than the first zone ECU 21 orthe third zone ECU 23 can be considered. On the other hand, when theallowable delay time of the airbag device D11 is more than or equal tothe predetermined reference time (the communication delay time T10) (NOin step S19), the flow proceeds to step S21, and it is determined thatthe operation-signal generation unit of the airbag device D11 can beincorporated in the central processing unit 10.

Returning to step S11, when NO is determined in step 311, that is, whenno protocol conversion is performed in the specified communication path,the flow proceeds to step S12. In steps S12 and S13, the communicationdelay time is estimated. Note that the process in step S12 is similar tothat in step S16 described above, and the process in step S13 is similarto the process in step S17 described above, and thus the detaileddescription thereof will be omitted here. In addition, as in step S11described above, in a case where it takes more time for each processthan the conventional ECU if the process is incorporated in the centralprocessing unit, the time can be included in the communication delaytime in step S14. When the processes in steps S12 to S14 end, the flowproceeds to step S19. Then, in step S19, for example, when the allowabletime of the airbag device D11 is less than the predetermined referencetime (the communication delay time T10) (YES in step S19), the flowproceeds to step S20, and the operation-signal generation unit of theairbag device D11 cannot be incorporated in the central processing unit10, and it is designed that the operation-signal generation unit(including the control output circuit) of the airbag device D11 isprovided (left) in the zone ECUs 21 and 22, or the smart ECU 161.

As described above, according to the present embodiment, the allowabletime that is allowed from when the operation information is input to theinformation acquisition unit to when the control signal of the actuatoris output is set in the actuator to be operated. The above embodimenthas described an example of setting the allowable delay time allowedfrom when a collision is detected by the collision detection unit 361 towhen the control signal of the airbag device D11 is output is set in theairbag device D11 corresponding to the actuator to be operated.According to the present embodiment, in a case where the allowable delaytime is less than a predetermined reference time, the operation-signalgeneration unit of the actuator is designed to be provided in the zoneECU 2. For example, in a case where the response speed after collisiondetection is required as in the airbag device D11, the allowable delaytime is set to be relatively short. As a result, when the allowabledelay time is less than the predetermined reference time, theoperation-signal generation unit of the airbag device D11 is designed tobe provided in the zone ECU 2. In this case, the airbag device D11corresponds to a second operation-signal generation unit. On the otherhand, in an illumination device such as a vehicle interior lamp or aheadlight, a sound device such as a buzzer, and the like, the allowabledelay time that is allowed from when the operation of the driver, theenvironment outside the vehicle, or the like is recognized to when thecontrol signal is output to the actuator to be operated can be set to berelatively long. As a result, when the allowable time is equal to orlonger than the predetermined reference time, it is determined that theoperation-signal generation unit can be incorporated in the centralprocessing unit 10, that is, the operation-signal generation unit can bedesigned to be provided in the central processing unit 10. In this case,the illumination device and the sound device correspond to the firstoperation-signal generation unit. By providing the allowable delay timeas described above, it is possible to roughly separate the function thatcan be incorporated in the side of the central processing unit 10 andthe function provided on the side of the zone ECU 2 before complicatedarithmetic processing or the like is performed.

Furthermore, the vehicle 1 is divided into a plurality of (seven in thepresent embodiment) zones, the zone ECU 2 is provided in each zone, andthese zone ECUs 2 are connected to construct a trunk network. Each zoneECU 2 includes a communication port, and the communication port isconnected to an in-vehicle device using a connector or the like. As aresult, the delay time between each zone ECU 2 and the centralprocessing unit 10 can be obtained in advance by simulation or the like.It becomes easy to set “predetermined reference time” serving as areference for providing the operation-signal generation unit on the sideof the first zone ECU, and the setting accuracy is also enhanced. In acase where the trunk network is configured in advance, design dataand/or simulation data such as communication delay information and/or aprotocol conversion time in the trunk network can be registered inadvance in a database (denoted as “DB1 to DB3” in FIG. 1.1), and thedata of the databases DB1 to DB3 can be referred to in each design flow.As a result, design efficiency can be increased, and high-speedprocessing can be performed.

Note that the technology disclosed herein is not limited to theembodiments described above, and various changes and substitutions canbe made without departing from the gist of the claims. In addition, theembodiments described above are merely examples, and the scope of thepresent disclosure should not be interpreted in a limited manner. Thescope of the present disclosure is defined by the claims, and allmodifications and changes falling within the equivalent scope of theclaims are within the scope of the present disclosure.

INDUSTRIAL APPLICABILITY

The technology disclosed herein is useful for designing a vehiclecontrol system.

REFERENCE SIGNS LIST

-   -   2 zone ECU    -   10 central processing unit

1. A design method for a vehicle control system including a plurality ofzone ECUs each of which is disposed in each predetermined zone of avehicle and a central processing unit that integrally controls the zoneECUs, the design method operating an in-vehicle device installed in thevehicle in accordance with an activation signal from an informationacquisition unit installed in the vehicle, the design method comprising:constructing a trunk network by connecting the central processing unitand the zone ECUs in a daisy chain layout; calculating a firstactivation time from when each network from a predetermined zone ECU ofthe zone ECUs to the central processing unit is sequentially activatedto when the central processing unit is activated; calculating a secondactivation time from when each network from the central processing unitto a predetermined zone ECU of the zone ECUs is sequentially activatedto when the predetermined zone ECU is activated; and determining aconnection destination of the information acquisition unit and aconnection destination of the in-vehicle device from the zone ECUs in amanner that a total time of the first activation time and the secondactivation time is less than a predetermined delay time.
 2. A designmethod for a vehicle control system including a plurality of zone ECUseach of which is disposed in each predetermined zone of a vehicle and acentral processing unit that integrally controls the zone ECUs, thedesign method operating an in-vehicle device installed in the vehicle inaccordance with an activation signal from an information acquisitionunit installed in the vehicle, where constructing a network byconnecting the central processing unit and the zone ECUs in a daisychain layout includes setting a network path of a first network and anetwork path of a second network in a manner that a total time of afirst activation time from when the first network from a first zone ECUof the zone ECUs, the first zone ECU receiving an activation signal fromthe information acquisition unit, to the central processing unit issequentially activated to when the central processing unit is activatedand a second activation time from when the second network from thecentral processing unit to a second zone ECU of the zone ECUs, thesecond zone ECU outputting a control signal of the in-vehicle device, issequentially activated to when the second zone ECU is activated is lessthan a predetermined delay time.
 3. A vehicle control system comprising:a central processing unit that integrally controls an operation of avehicle; and a plurality of zone ECUs connected to the centralprocessing unit in a daisy chain layout, the vehicle control systemoperating an in-vehicle device installed in the vehicle in accordancewith an activation signal from an information acquisition unit installedin the vehicle, wherein the zone ECUs include a first zone ECU to whichthe information acquisition unit is connected and a second zone ECU towhich the in-vehicle device is connected, and the first zone ECU and thesecond zone ECU are set in a manner that a total time of a firstactivation time from when the first zone ECU receives the activationsignal from the information acquisition unit and a first network fromthe first zone ECU to the central processing unit is sequentiallyactivated to when the central processing unit is activated and a secondactivation time from when the central processing unit is activated and asecond network from the central processing unit to the second zone ECUis sequentially activated to when the second zone ECU is activated isless than a predetermined delay time.